溴酸钾-溴甲酚紫催化光度法测定水中痕量亚硝酸根

Kinetic Spectrophotometric Determination of Nitrite by the Catalytic Oxidation of Bromocresol Purple with Potassium Bromate

基于在 0 .45mol mLH3PO4 中NO-2 对KBrO3氧化溴甲酚紫的催化褪色反应 ,建立了测定NO-2的新方法。发现温度仅对反应初速有较大影响 ,但在 1 0～ 2 2min及 2 0～ 2 8℃范围内ΔA趋于恒定 ,温度及时间几乎无影响。在反应 1 2min后于 43 4nm测定NO-2 ,线性范围及检测限分别为 0 .0 1～ 0 .4mg L及9μg L。多数常见离子无干扰。Fe 可用NaF掩蔽 ,V 及基体干扰可加尿素制备空白样予以扣除。本法简便 ,灵敏度及选择性较高 ,用于水中痕量NO2- 的测定 ,结果满意。

A kinetic spectrophotometric method for the determination of nitrite was developed, based on the catalytic oxidation of bromocresol purple with KBrO3 at 22 similar to 28 degrees in 0.45 mol/mL H3PO4 medium. The temperature had great effect only on the initial reaction rate. The DeltaA kept constant during 10 similar to 22 min. Fixed at 12 min, the linear range and detection limit for nitrite at 434 rim were 0.01 similar to0.4 mg/L and 9 mug/L, respectively. Most of the common ions did not interfere. Fe(III) could be masked with NaF. The effect of V(V) was eliminated by preparing blank sample solution with urea. The method is sensitive and selective. It was applied to the determination of trace nitrite in water with satisfactory results.